Contribution of Leu and Hyp residues to antioxidant and ACE-inhibitory activities of peptide sequences isolated from squid gelatin hydrolysate

Abstract

** This centre has implemented and maintains a Quality Management System which fulfils the requirements of the ISO standard 9001:2000 AbstractSquid gelatin obtained from inner and outer tunics was hydrolyzed with Alcalase to isolate antioxidant peptide sequences. The ACE-inhibitory activity of the isolated peptides was also evaluated. After fractionation by ultrafiltration and size-exclusion chromatography into four fractions, the antioxidant activity of the peptide fractions was determined by radical scavenging ability and ferric reducing power. Fraction FIII showed the highest antioxidant activity, although slight differences could be expected in the antioxidant activity of the different fractions based on the amino acid composition.FIII was subjected to liquid chromatography and tandem mass spectrometry (LC-MS/MS) and two major compounds were identified: the compound with m/z 952.42, which could be mostly comprised by the carbohydrate fucose, and the peptide with m/z 1410.63. Three possible sequences were proposed for this peptide, and the contribution of Leu or Hyp residues to the antioxidant and ACE-inhibitory activities of the resulting sequence was evaluated. The presence of Leu residues in the peptide sequence in *Manuscript Click here to view linked References 2 replacement of Hyp seems to play an important role in the antioxidant and ACEinhibitory activity.

Antioxidant peptides isolated from sea cucumber Stichopus Japonicus

“…This balance was showed in this peptide, the hydrophilic amino acids were 7/15 and the hydrophilic amino acids were 5/15. The sidechain of Gly consists of a single hydrogen atom and may confer high flexibility of the peptide to capture radicals, which was also suggested by Alemán et al [28]. In addition, it was reported that bioactive peptides usually contain 2-20 amino acid residues per molecule, and the lower the molecular weight, the higher their chance to cross the intestinal barrier and exert biological effects [40,41], and the peptide in this study was composed of 15 amino acid residues.…”

“…Generally, aromatic amino acids in peptide sequences can donate protons easily to electron-decent radicals, so they are believed to be effective radical scavengers [27]. However, the amino acid compositions from collagen to gelatin hydrolysates are rich in residues of Gly, Ala, Pro, Hyp, Glx and Asx, but poor in Met, Cys, His and Tyr [28][29][30]. Many peptides from collagen hydrolysis have been described to have antioxidant capacity without containing any of the above-mentioned proton-donating amino acid residues in their sequences [24,31].…”

Collagen from jumbo squid fin: extracting conditions and influence of the protease system on collagen hydrolysate antioxidant activity

“…In fact, several studies have reported that compounds with biological and functional properties are found at high concentration in squid discard, having potential applications in the medical, food, mixed-feed, microbiological, and other industries (Alemán, Giménez, Pérez-Santin, Gómez-Guillén & Montero, 2011;Nakchum & Kim, 2015;Ramasamy, Subhapradha, Shanmugam, & Shanmugam, 2014). The main byproduct from jumbo squid is the skin, and it is the most studied.…”

ACE inhibitory activity of pangasius catfish (Pangasius sutchi) skin and bone gelatin hydrolysate

“…Several natural ACE inhibitory peptides have been isolated from collagen and gelatin enzymatic hydrolysate of various food protein sources such as porcine skin collagen (Ichimura et al 2009), bovine skin gelatin , fish skins Nagai et al 2006;Park et al 2009), fish cartilage (Nagai et al 2006), scales (Fahmi et al 2004), squid (Alemán et al 2011) and sea cucumbers protein hydrolysates (Zhao et al 2007) as an alternative approach to the synthetic ACE inhibitory drugs.…”